Over the years, many devices have been provided which are useful in the field of vision correction. Generally, the end result of the vision correction process is the production of a pair of spectacles for a user. The spectacles fit on the user's face, and include a spectacle frame. Within the spectacle frame are mounted left and right lenses which may provide for optical correction of the user's vision. The right lens provides the optical correction for the user's right eye (if necessary) and the left lens provides the correction for the user's left eye (if necessary).
Three pieces of information are essential for providing spectacles for the user which provide for effective vision correction. A first piece of information is a lens prescription. This piece of information defines the vision correction provided by the left and/or right lens. Two additional pieces of information are necessary for properly fitting vision correction. One of these is the interpupillary distance, i.e. the distance between the user's eyes. Finally, in the case where the user's optical correction includes a bifocal or multifocal lens, it is necessary to relate the optical center of the bifocal or multifocal lens with respect to the frame in which it is mounted. In this application, this relationship is termed bifocal segment placement (for a bifocal lens) or multifocal centering (for a multifocal lens), or generally as bifocal/multifocal centering.
Both the interpupillary distance and the bifocal/multifocal centering are specific to the user for whom the vision correction is intended.
Because vision-correction is important to a large segment of the population, there are service providers who make the measurements and, in some cases, provide spectacles in accordance with the measurements.
In some forms of spectacle-dispensing businesses, it would be useful if the interpupillary distance measurement and the bifocal/multifocal centering measurement could either be made by the user or indicated by the user. In some cases, this information will negate the requirement that the user physically visit the spectacle dispensary.
It is accordingly one object of the present invention to provide a device allowing a user to make or indicate the interpupillary distance measurement. It is another object of the present invention to provide a method by which a user can either make or indicate the interpupillary distance measurement. It is another object of the present invention to provide a device for assisting the user to make and/or indicate the bifocal/multifocal centering measurement. It is another object of the present invention to provide a method of allowing a user to make or assist in making the bifocal/multifocal centering measurement. To make or assist in the measurement, a bifocal/multifocal centering assist device is provided.
In accordance with one embodiment of the invention, a device for making or assisting in the making of the interpupillary distance measurement is provided. This device will be referred to as the interpupillary distance measurement assist. The interpupillary distance measurement assist in accordance with one form of the invention includes three major elements: a frame and a pair of slidable members. The frame includes a notch so that the frame can be conveniently supported on the nose of a user. The slidable members include a left slidable member and a right slidable member, each capable of being supported by the frame for horizontal movement relative to each other and relative to the frame. Each of the slidable members includes a small hole, sometimes referred to as a viewing hole, therein.
In use, the user places a viewing target on a convenient vertical surface at approximately eye level. The user then stands approximately 8-10 feet from the vertical surface supporting the viewing target and places the frame so that it is supported by the user's nose. The slidable members are moved relative to each other and relative to the frame so that the user can view the viewing target through each hole in the slidable member. At this point, the distance between the viewing holes is a measure of the user's interpupillary distance. With the frame and slidable members configured so that the user can view the viewing target through each hole, the slidable members are fixed relative to the frame. Thereafter, the user can remove the frame and easily measure the distance between the viewing holes. Alternatively, the frame and slidable members fixed relative thereto can be returned to a spectacle dispensary where the interpupillary distance can be readily measured.
As will be described hereinafter, the interpupillary measurement assist device can be manufactured for one-time use. The frame can be stamped or cut from a unitary piece of paper stock. As will be described hereinafter, the frame is generally rectangular but has an oval cut-out therein which will form a notch after the frame is properly assembled. The frame blank has first, second and third portions. Because the first, second and third portions of the frame are portions of a common rectangular blank, they all have a common length. The width of the first portion is reduced in part by the cutout which will form the notch. The second portion of the blank is directly adjacent the first portion and therefore has a cutout which is complementary to the cutout of the first portion. The first, second and third portions are then folded about first and second fold lines and secured by any convenient securing arrangement. Because the frame means comprises first, second and third portions, when properly folded, a pair of channels is formed, each for receiving one of the slidable members. This allows the slidable members to slide within a dedicated channel without interference from the other slidable member.
The slidable members are L-shaped and may be cut from the same paper stock. Each of the holes in the slidable member is formed in the base, as will be apparent from the drawings.
In accordance with another embodiment of the invention, the bifocal/multifocal centering measurement assist device is formed from paper stock so that it is disposable. Because the measurement designed to be revealed by the bifocal/multifocal centering device assist is related to the frame, the bifocal/multifocal centering device assist is designed to be used in conjunction with the spectacle frame chosen by the user. The bifocal/multifocal centering device assist includes a frame including a first pair of parallel legs separated by a second pair of parallel legs for defining a viewing window between the pairs of parallel legs. The bifocal/multifocal centering device assist also includes a convenient attachment for attaching the frame to a lens mounted in the spectacle frame. Typically, the lens will be a manufacturer's demonstration lens, i.e. the lens does not provide for vision correction. The attachment conveniently is adhesive-based. The bifocal/multifocal centering device assist also includes a slider having a slit therein. The slider has a length which is longer than one dimension of the frame and a width which is smaller than another dimension of the frame so that when the slider and frame are mated, in use, there is a vertically adjustable viewing position defined by the location of the slit portion of the slider within the viewing window defined by the frame.
In use, the user first positions a viewing target on a vertical surface at approximately eye level. The user then attaches the frame to a lens in the spectacle frame and places the spectacle frame in a normal using position supported on the user's face. The slider is placed between the horizontal legs of the frame and the lens to which it is secured so that the slit provides a viewing position at a vertically-adjustable location within the viewing window defined by the frame. The user then adjusts the vertical position of the slider so that the viewing target is centered in the visual area. At this point, the user can merely make the necessary measurement, measuring the vertical position of the slit relative to the frame. Typically, however, the user, rather than actually making the measurement, merely secures the slider to the frame and returns the entire combination, i.e. spectacle frame, frame and slider secured to the lens of the spectacle frame, to the dispensing business where the measurement can be made.